Conflict of the Heart
by CeceliaStar
Summary: Detective Natsu Dragneel is ready to take down Lucky Lucy, a front for arms trafficking. What will happen when he falls head over heels for one Lucy Heartfilia, daughter to the notorious crime boss? Nalu. (Story idea from tumblr user Mushi0131. You can blame them for this. K because I'm not sure whether this will contain NSFW yet.)
1. Chapter 1: Mind if I sit here?

**Thanks to Tumblr user mushi0131 who wanted a story written with this prompt, and who am I to argue? I'm a sucker for nalu and writing stories when I have 10 others that aren't completed.**

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He'd been staring furiously at the papers all day, trying to commit all the information they contained to memory. It was like throwing a bunch of darts at a board and hoping they all stuck. Natsu had never been good at darts but he was a good detective and this was possibly the biggest bust of his career. He'd do whatever it took to take them down, even if it meant memorizing every detail about the fake company, Lucky Lucy, and the companies CEO and daughter.

Natsu leaned back in his too small chair and stretched, feeling every joint in his body crack. Sitting at a desk all day was not what he signed up for when becoming a detective, but as with most things in his life, not a lot went according to plan. Besides, soon enough he'd be out in the field.

"Too much for you, Natsu?" Gray asked, raising his eyebrows, smirking. "If you can't handle it I can gladly take over. You've never been much with the ladies after all."

Gray, Natsu's deskmate, and longtime partner, had to be the cockiest and most insufferable person he'd ever met. Coincidentally, Gray felt the same way about Natsu.

"Shut your trap," Natsu growled, cracking his neck. "You couldn't handle this if Heartfilia gave you his transaction logs himself."

Jude Heartfilia, owner of the company Lucky Lucy, a business that made and sold locks and keys, was a front for arms trafficking to distant countries, or at least that's what the police suspected. They'd been investigated for years with no full proof evidence, driving the police up the walls. But there was finally a break in the case when it was revealed that Jude had a daughter, something he'd clearly been trying to keep a tight lid on. Word spread fast when it came out that a girl with the same likeness and last name as him had published a book and worked at a huge newspaper in town.

Gray ignored the invitation for a fight if only because Makarov, their captain was watching with narrowed eyes. One raised fist and they'd both be forced to desk duty for the rest of their lives.

"You know," Gray drawled, leaning closer to Natsu over their desks, "I hear the daughter is quite a catch. Make sure not to fall in love, yeah?"

Natsu snorted. He glanced back down at the file on his desk containing all the information about dear old Lucky Lucy Heartfilia. Twenty-three, a year behind him, she grew up isolated from the world and kept completely secret. Not much is known about her before she got a job at a newspaper company and published a book that sold over a million copies just a few months ago.

Natsu's task was simple. Go undercover, gain her trust and then, of course, take down one of the most renowned arms trafficking businesses.

He wasn't sure how much she knew about her father's business, but since she still lived with him, it at least gave him an in. He'd do whatever it took to take them down.

"Fat chance," Natsu drawled back. "I'm more concerned about _her_ falling in love with _me,_ " he snickered. His amusement was short-lived when he felt a sharp slap hit him in the back of the head.

"Don't you dare play with a woman's heart, Natsu," a sharp voice commanded. Natsu flinched and turned. Erza, their sergeant stood over him, glaring daggers. He nodded quickly, not bothering to explain that he was joking; it likely wouldn't help. Erza wasn't one for humor when it came to love. Seeming satisfied, she said, "Are you ready, Natsu? You should head out soon."

Natsu glanced down at his watch. Nearly noon.

Nodding, he stood and grabbed his jacket, leaving his gun and badge on the desk. Instead of the tie and semi-professional clothes he usually wore, he'd donned a casual T-shirt and jeans with sneakers, perfect for the occasion. His died pink hair was left loose instead of slicked back like usual.

Levy, their resident nerd and computer programmer, called a quick good luck as he stalked out of the bustling station. He grinned, feeling the adrenalin rush through his system. Here were his first few steps to the biggest bust in his career.

It was a couple block walk, enough to make him start to sweat under the beating sun. Natsu was secretly grateful for it. The more he looked like a guy coming straight off the street, the better.

Finally, he arrived at his destination. A little café snugged between a bookstore and a small grocery store. Every Wednesday Lucy Heartfilia showed up at noon, sat in a corner and wrote.

It only took him a second to locate her head, bent over the table, writing furiously in a notebook. He ordered a cup of coffee and walked towards her. He stopped in front of her and smiled in amusement when she didn't even notice him. He cleared his throat, causing her head to snap up in surprise.

"Mind if I sit here?"

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 **Comments, suggestions, reviews? Yes, no, maybe so?**

 **I know. You're like, if you're gonna write update Heartfilia Home or Finding the Stars or What Our Hearts Want but listen I'm trash soooo idk what to tell ya. Anyway tell me your thoughts.**

 **If you hated it, well I wrote it at 4 a.m. so chill. I can only do so much**

 **Anyway, hope you enjoyed! (You can blame** **mushi0131 for this travesty). I'll update soon, hopefully!**

 **Love ya~**


	2. Chapter 2: Are You a Beaver? Cause dam!

**I'm trash, I missed my babes. Writing them being cute is me being completely indulgent. I'm a college student so do I have 1,000 different things I should be doing before updating this? You fucking bet ya. Am I gonna be a responsible adult? Fuck no.**

 **Don't come to expect quick updates like this though, I'm, again, trash. Inconsistency is my middle name.**

 **Enjoy~**

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One of the number one rules in an infiltration game is to give a fake name, so if discovered, they can't track down your real identity. Natsu had planned to use the name Jared, but the moment Lucy asked, his real name leapt from his tongue before he could catch it. He told himself it was because he'd never done an undercover mission before, because he wasn't used to lying about who he was.

The reality was that Lucy's eyes were sharp and would likely detect any lie. Not only that, but just one look at her had him feel immense guilt for every lie he'd eventually spout.

It was a truth he was unwilling to face, mainly because this entire operation depended on him lying. He wasn't willing to admit failure so early in the game. So, he decided that giving his real name would have to be a concession he made, but it would be the last one.

Lucy was naturally suspicious. Maybe that came from growing up with a crime boss father, maybe from something else entirely, but it was ingrained in her DNA as far as he could tell. The moment he showed up she looked him up and down, assessing for a threat. She must have decided he wasn't a threat though, because she invited him to sit moments later.

"I'm Lucy," she smiled, gently setting her pen down on her notepad after he'd clumsily let his real name slip. She took in his outfit and pink hair. "I haven't seen you here before."

Natsu chuckled nervously and scratched the back of his head. "Just sort of stumbled on this place. You come here often?"

Immediately his face reddened. What kind of line was that? He wasn't supposed to be hitting on the girl, just getting close. And even if that was his task, he'd just stumbled into the lamest of the lame, the all-time failure of pickup lines. He wanted to dunk his head in a bucket of ice to get rid of the heat that set his face aflame. To his astonishment, she giggled.

"That's all you've got?" she laughed, eyes crinkling in amusement. She leaned forward, her blonde hair falling over her shoulders, a small smile set permanently on her lips. "You'll have to do better than that."

But by the way her beautiful eyes were sparkling, Natsu already felt like he'd hit the jackpot. She was pretty, much prettier then his files pictures would suggest. Natsu felt his heart stutter as she continued to smile at him. This wasn't good.

Licking his lips, he paused, then grinned. He could feel the mischief bubbling in him like a boiling pot of water.

"I must be a snowflake, because I've fallen for you." Natsu winked and Lucy covered her mouth in mortification.

"No!" she cried.

"You spend so much time in my mind, I should charge you rent."

"Oh my god."

"Are you a beaver? Cause daaaaaaaam!"

"Please, oh my god."

"Is your body from McDonald's? Cause I'm lovin' it!"

"Natsu, no."

"Well, here I am. What were your other two wishes?"

By now, Lucy was leaning over the table, loud laughter peeling from her throat as tears trickled down her cheeks. Natsu couldn't help but laugh in return until they were both laughing themselves hoarse. The entire café turned and glared at the both but neither cared.

Their roaring eventually turned to quiet giggles until they both found themselves staring at the other, wide grins on their faces.

Her eyes were brown, but upon further inspection, he realized that they held a rainbow in them. He could see flecks of gold and yellow, a bit of green. They were the kind of eyes he could easily lose himself in.

Natsu realized he was staring and awkwardly cleared his throat and gestured at her journal.

"Whatcha writing?"

Her good mood dissolved immediately into a more bitter expression. She grabbed it and pulled it to her chest as if protecting herself from something.

"Nothing worth anything," Lucy said quickly.

Natsu very much doubted that but resisted the urge to dig further. It could have information on Jude, information that could bust this case open. But digging would make her pull away and he couldn't afford that. The slow game it was.

"Weirdo," Natsu sighed teasingly. Lucy scowled and Natsu panicked, wondering if he'd gone too far, ruined it already.

" _Weirdo_ ," she scoffed. "Who's the one with pink hair?!"

His eyes widened in outrage. "My hair isn't _weird,_ it's cool!" Lucy cracked a smile and the detective in Natsu sighed with relief but another part, one he was going to ignore, begged to smile back.

"Who thinks pink hair is cool?" she snorted.

"Everyone!"

"You're delusional."

"No, you are!"

Lucy stuck her tongue out, so he responded in kind. Despite himself, he found himself grinning once more at her.

Lucy was a lot more fun then he'd anticipated.

There were about a hundred different reasons that spelled trouble for him. But he couldn't find himself to care.

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 **Comments, suggestions, reviews? Yes, no, maybe so?**

 **They're so cute I love them. Makes me miss being in a relationship lol. Tell me your thoughts please or how will I have the will to go on?**

 **Peace children~**

 **PS mushi0131: I'm glad you liked it! Not sure how much of your ideas from the tumblr post I'll get in this. We'llllll seeeeee. I'll do my best to keep up with this because writing these two happy gives me life. I loved that you woke up to this. I can check that off as my one good deed for the day lol. Anyway, thanks for the inspiration :p**


	3. Chapter 3: Thank God It's Not Your Penis

**This is from Lucy's POV. Figured if we want to truly enjoy this we need to get a good look at Natsu from her perspective ;)**

 **Enjoy!**

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Lucy was a practical girl. Sure, she loved a good romance or adventure story. Anytime a book popped up in the library about some unbelievable event she gobbled it up like food. And clichés were like cake – she just couldn't resist. But that was in fictional worlds. In real life she looked at things with a very practical eye.

How could she not, when her father practically beat into her to look at things like a puzzle that she had no choice but to solve?

Past boyfriends were chosen on their similar interests rather than feelings and passion. Food choices were made depending on prices. Life was a puzzle and she was excellent at putting them together. Lucy never had that heart-pounding excitement she wrote about and read so often. Had never been kissed breathless, never felt fire flood her veins at just the slightest touch. Never truly bought into that.

But here she was, being the most cliché character in the book.

Every Wednesday she'd wait in anticipation for Natsu to show up. He'd shown three times already, and it didn't seem like he was planning to stop. She'd even considered coming more often than just Wednesday, but her work schedule didn't allow it. Neither did the practical side of Lucy. She wouldn't change her schedule for some random guy. She just wouldn't.

But every day she thought of him, of his fanged grin, his dark eyes that practically burned with life and intensity, of the dragon tattoo that she'd occasionally see peek out from under his jacket and curl around the base of his neck.

Soon, she knew, her practical side was going to lose as her heart fought with a savagery she'd never seen before. Lucy had nearly suggested they meet outside of the coffee shop, but each time she'd hesitated, and ultimately dismissed the idea. Maybe certain things were better left as they were.

He'd been tempting her lately, though. She pretended not to notice, but she was hyperaware when he'd drop hints about doing things outside of the café. He spent a lot of time talking about his cat, and how he was sure Lucy would love him. And oh, had she heard about this little bookstore across town? (She had.) And how he hated going grocery shopping but how much better it would be if she went with him.

Each time he'd look at her and smile warmly and then her insides would turn to a goop she had no chance of molding back to solid organs. But instead of agreeing she'd laugh it off like a coward.

Lucy sighed and settled back against the headboard of her bed. It was a long day of work and a long day of writing on her second book that fought like hell against her to not be written.

She still wore her work clothes, professional and stiff, but she didn't even bother changing. The moment she'd arrived at home she'd run for her room, hoping to not see her father, and flopped on the bed like the mattress was made for her. Knowing her father, it most likely was.

Lucy's eyes drifted to the notepad next to her bed, sitting on the nightstand, innocent with its blue cover dotted with golden stars, and frowned. Every time she looked at it a sour mood filled her stomach and she fought the urge to vomit.

Ripping open one of the drawers she shoved it in and slammed it closed.

Lucy stood, shaking off the gross feeling, and walked to her bathroom to take a shower. As the hot water hit her skin a sigh once again left her. If she could manage the rest of the night without seeing her controlling father, she'd consider it a good one.

When she was done, wrapped in a towel and dripping, she sat back on her bed and rolled her shoulders. Today had been tough. Especially with the knowledge that she wouldn't see Natsu again until next week. She decided to not acknowledge that.

And then her phone lit up with a text.

The moment her hands grasped the phone a little breath left her lungs as her heart sped up.

 _Lucy let out a laugh as he held out his hands insistently._

" _What, want a treat?" she giggled. Natsu frowned._

" _Give me your phone." Lucy paused and cocked her head._

" _Why?"_

" _Don't you trust me?" he pouted._

 _Lucy let out a huff. This was their third time hanging out and he was already asking so much from her. He was still a stranger! But that was her practical side talking. The side consumed by her heart was telling her that he was on the fast ride to becoming her best friend, someone she would care about immensely. Being with him was so easy, far easier than being with anyone else she knew. That fact scared her._

" _Fine." She was really bad at saying no when he looked at her like that. She reluctantly handed over her phone. The small star attached to her case jingled. Natsu took it eagerly and then frowned when he looked down at it._

" _What's your password?"_

 _Rolling her eyes, she snatched it back and typed in her mother's name before handing it back. He grinned down at it as he typed, and Lucy shifted nervously, fighting the urge to take the phone back, wondering what kind of mischief he was up to now. A few seconds later he handed it back, looking satisfied._

" _What'd you do?" she asked, eyeing her phone suspiciously. Her eyes fell on her contact page, where a new name had been added. His name._

 _He grinned cheekily at her and waved his phone._

" _Now I can send you pictures of my cat!"_

Lucy hesitantly opened the text. There was indeed a photo of a cat (thank god it wasn't a penis photo. Natsu didn't seem like that kind of guy but you never know, and his "cat" could easily be an innuendo for his dick). Still, Lucy blanched at the picture.

Why was his cat _blue_?!

Attached to the picture were the words, "Hey Luce! This is Happy"

Despite herself, Lucy smiled.

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 **Comments, suggestions, thoughts? Yes, no, maybe so?**

 **I just love them. I'm going to try and make the chapters longer for y'all. It's always more fun to open up an update to a good, long, juicy chapter. I'm making this up as I go btw so if I have to change anything I'll let you guys know.**

 **Please review! Every time I read a review my heart bleeds with happiness and I finally feel like my life has meaning (college sucks a person's soul out what can I say). I was literally walking to class and grinning because of the reviews despite my impending doom (I had a test). You guys make me really happy, I don't deserve it. Please tell me your thoughts!**

 **Love ya~**


	4. Chapter 4: Got Impatient

**Sorry for the wait I'm a lazy garbage monster in the shape of a human**

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Natsu shifted uncomfortably in his plastic seat, back straight and fists clenched. This would not be good. In no way could this turn out well for him.

"Detective."

Natsu began thinking of many things, things that were decidedly not where he sat and what he was facing. No, because focusing on what was happening was something he very much did not want to do.

"Natsu," Makarov growled. Natsu continued staring at the wall, away from his Captain. "Listen boy, I don't know what got it in your head to do this, but it was certainly not common sense."

"This" being the fact that Natsu had went ahead and infiltrated Jude Heartfilia's mansion without express permission from his Captain and without proper supplies in case things got dicey. "This" being the allure of a certain blonde headed writer who knocked what little common sense he had from his brain. "This" being his worry for her staying in such a place and wanting to get her out. "This" being him throwing caution out the window and trying to get into the mansion to track down evidence. "This" being Natsu getting caught in the fence, nearly caught, and chased by attack dogs for nearly two blocks, only for him to jump in a trash can and shake them from his trail. "This", being his own personal hell.

"So?" Makarov demanded.

He wanted to know why Natsu had been reckless. Why he'd attempted a completely illegal act and obtained evidence without proper cause. All Natsu could say that every time he saw Lucy his heart stuttered and every time he received a text a grin would automatically light his face. All he could say that every moment the investigation dragged on would be another stab to her heart when she realized the truth and every moment he ached to share his life with her, but he couldn't, not until this business was dead in a drawer.

But he couldn't say that.

"Got impatient," was all he muttered, sinking slightly into his chair. Which was very true. Just not completely.

Makarov narrowed his eyes and leaned over.

"If caught you would have compromised the _entire_ investigation. I don't care how impatient you get, one more attempt like this and you're done."

Natsu paled considerably.

"Done, as in off the case?" he asked, panic clutching his heart.

"Done, as in this precinct. As in, fired, done." Makarov growled. "You're on thin ice boy."

Natsu gulped, back snapping straight. He couldn't imagine a life not on the force. He'd always been a wrecking ball in his life – always in trouble at school, never caring enough for his schoolwork to even try, constantly in fights. "Problem kid" was his reigning title. But here he'd finally found a place to fit in. Natsu couldn't fathom a day where he didn't come here for work.

Natsu nodded quickly.

"Understood, sir."

Makarov sighed and rubbed his forehead. "I swear, Natsu, one day you'll kill me." Natsu fought back a grin at that. The entire precinct caused him ultimate stress, but he was sure Makarov wouldn't have it any other way. "So," he paused, "how goes your project? I assume not well, given current… incidents."

Natsu cleared his throat nervously.

"Lucy Heartfilia is what we imagined – well connected with her father. I'm still working on gaining her trust. It is slow going, she's guarded." Natsu shifted, feeling uncomfortable. This felt so wrong, talking about her like this.

"Do you think we should abandon this method and find another way?" Makarov questioned, head tilting to the side.

Natsu wanted to say yes. The sooner he could abandon this project the sooner he could be honest with Lucy and have a real relationship. But he remembered that notebook that she guarded so closely and the way she avoided speaking of her father. She was hiding something, and it could be crucial.

"I just need more time," he sighed, defeated. "She knows something. It's just a game of patience at this point."

Makarov nodded and leaned back in his chair, seeming satisfied.

"Let me know if you need anything." Makarov nodded at him in dismissal and Natsu stood, grateful to finally be released.

Just as Natsu began to sink into the chair at his desk, he felt his phone buzz. Glancing down curiously, he felt a small smile light his face.

"Wanna grab lunch? – Lucy H."

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 **Comments, suggestions, thoughts? Yes, no, maybe so?**

 **I'm terrible at keeping promises for things to be longer - apologies. The writing spirit is being a bitch today, what can I say. Also, interest in this story has DESPERATELY dropped lol. I'm still gonna write it but damn son where did I go wrong? Meh, who cares.**

 **Anyway, let know your thoughts, hope you enjoyed! Needz the angst.**


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